The permeation of oxygen ions through ceramic ion transport membranes is the basis for the design and operation of high-temperature oxidation reactor systems in which permeated oxygen is reacted with oxidizable compounds to form oxidized or partially-oxidized reaction products. The practical application of these oxidation reactor systems requires membrane assemblies having large surface areas, flow passages to contact oxidant feed gas with the oxidant sides of the membranes, flow passages to contact reactant feed gas with the reactant sides of the membranes, and flow passages to withdraw product gas from the permeate sides of the membranes. These membrane assemblies may comprise a large number of individual membranes arranged and assembled into modules having appropriate gas flow piping to introduce feed gases into the modules and withdraw product gas from the modules.
Ion transport membranes may be fabricated in either planar or tubular configurations. In the planar configuration, multiple flat ceramic plates are fabricated and assembled into stacks or modules having piping means to pass oxidant feed gas and reactant feed gas over the planar membranes and to withdraw product gas from the permeate side of the planar membranes. In tubular configurations, multiple ceramic tubes may be arranged in bayonet or shell-and-tube configurations with appropriate tube sheet assemblies to isolate the oxidant and reactant sides of the multiple tubes.
The individual membranes used in planar or tubular module configurations typically comprise very thin layers of active membrane material supported on material having large pores or channels that allow gas flow to and from the surfaces of the active membrane layers. The ceramic membrane material and the components of the membrane modules can be subjected to significant mechanical stresses during normal steady-state operation and especially during unsteady-state startup, shutdown, and upset conditions. These stresses may be caused by thermal expansion and contraction of the ceramic material and by dimensional variance caused by chemical composition or crystal structure changes due to changes in the oxygen stoichiometry of the membrane material. These modules may operate with significant pressure differentials across the membrane and membrane seals, and stresses caused by these pressure differentials must be taken into account in membrane module design. In addition, membrane modules have upper temperature limits above which membrane degradation and/or module damage may occur. The relative importance of these phenomena may differ depending on the specific oxidation reactions and operating conditions used. The potential operating problems caused by these phenomena may have a significant negative impact on the conversion efficiency and membrane operating life of the system.
There is a need in the field of high temperature ceramic membrane reactors for new membrane module and reactor system designs that address and overcome these potential operating problems. Such designs should include features to allow long membrane life, minimum capital cost, and efficient operation over wide ranges of production rates. Embodiments of the invention disclosed and defined herein address these needs by providing improved module and reactor designs for use in membrane oxidation systems.